Xiao Jc

Angiomyolipoma of the kidney. Immunoreactivity with HMB‐45. Light‐ and electron‐microscopic findings

Immunoreactivity with HMB‐45 has recently been described in renal angiomyolipoma, a tumour of smooth muscle cells. HMB‐45 is a monoclonal antibody that reacts specifically with melanosomes. In order to determine whether the tumour cells contain melanosomes and synthesize melanin, seven tumours were studied by light microscopy and immunohistochemically with the antibodies HMB‐45, KP1 (CD68), PG‐M1 (CD68), Ki‐M1P, anti‐lysozyme, anti‐smooth‐muscle actin, anti‐vimentin, anti‐S100 protein and KL1 (anti‐keratin). Two tumours were also studied by electronmicroscopy and one by immuno‐electronmicroscopy. Histochemical investigation for dopa oxidase was performed on cryostat sections. The tumours contained varying numbers of HMB‐45‐positive muscle cells. Reactivity was noted in lysosomal granules and rough endoplasmic reticulum. Typical premelanosomes were found in the tumour cells by electronmicroscopy. Groups of tumour cells stained for dopa oxidase. The tumour cells were not reactive for lysozyme, but reacted with KP1, PG‐M1 and Ki‐M1P. Immuno‐electronmicrosopy showed that reactivity for KP1 was located within lysosomal granules. The findings show that the tumour cells of renal angiomyolipoma contain premelanosomes and that they are able to synthesize melanin, because they contain dopa oxidase. Immunoreactivity with KP1, PG‐M1 and Ki‐M1P can be attributed, in the absence of staining for lysozyme, to the large number of lysosomal granules. The tumour cells were not found to be related to macrophages or myeloid cells.

Small epithelial cells in human liver cirrhosis exhibit features of hepatic stem-like cells: immunohistochemical, electron microscopic and immunoelectron microscopic findings.

Aims:  To investigate whether cells with features similar to those of the oval cells of rodents and the small epithelial cells (SEC) recently described in certain human liver diseases, i.e. hepatic progenitor cells, also occur in human liver cirrhosis.

Immunoreactivity of normal and neoplastic human tissue mast cells with macrophage-associated antibodies, with special reference to the recently developed monoclonal antibody PG-M1

There is increasing evidence in favor of the hypothesis that human tissue mast cells (MCs) are progeny of hemopoietic stem cells and are closely related to cells of the mononuclear phagocyte system. To test this hypothesis we investigated the immunoreactivity of normal/reactive MCs in 12 lymph node and tumor specimens and neoplastic MCs in 27 tissue samples from patients with various types of mastocytosis (urticaria pigmentosa, n = 13; cutaneous mastocytoma, n = 4; systemic mastocytosis, n = 6; and malignant mastocytosis, n = 4) with a panel of eight antibodies that stain macrophages or immune accessory cells and are reactive on routinely processed (paraffin-embedded, formalin-fixed) tissue. The MCs were stained by three of the macrophage-associated antibodies (namely, KP1 [CD68], Ki-M1P, and PG-M1 [CD68]), but were not stained by three other antibodies (namely, HAM56, MAC387, and LN5) or antibodies detecting immune accessory cells (DAKO-CD35 and anti-S-100 protein). While KP1 stained normal/reactive and neoplastic MCs in all the specimens investigated, Ki-M1P stained neoplastic MCs in nearly all the cases of mastocytosis but did not stain normal/reactive MCs. PG-M1 also failed to stain normal/reactive MCs and stained MCs in only approximately half of the specimens from cases of mastocytosis. Among these were most of the cases of systemic and malignant mastocytosis, but only a minority of the cases of cutaneous mastocytosis and a very few cases of urticaria pigmentosa. To summarize, (1) MCs display immunohistochemical staining properties resembling those of cells of the mononuclear phagocyte system but not those of macrophage derivatives belonging to the immune accessory cell compartment, and (2) PG-M1 and Ki-M1P are unique among the macrophage-associated antibodies investigated in that they do not stain normal/reactive MCs but exhibit preferential reactivity with the more atypical MCs in cases of systemic and malignant mastocytosis.

Congenital epulis and granular cell tumor : a histologic and immunohistochemical study

OBJECTIVES Although it is now reasonably certain that granular cell tumors derive from Schwann cells, the histogenesis of congenital epulis, which is largely isomorphic with granular cell tumor, remains unclear. A study was undertaken to compare the immunophenotype of these tumors with particular emphasis on the expression of matrix proteins and macrophage markers because such information is not available in the literature. STUDY DESIGN Four granular cell tumors and two congenital epulis were immunostained with a panel of 29 antibodies. Two congenital epulis and one granular cell tumor were investigated by electron microscopy, the latter also by immunoelectron microscopy. RESULTS Many similarities in immunostaining were found, for example, both tumor types were CD68+, Ki-M1P+, lysozyme-, vimentin+, fibronectin+, laminin+, lectin PHAE+, and lectin WGA+. However, differences were also noted, for example, granular cell tumor was always S100 protein+, but only one congenital epulis case was reactive (weak reactivity after microwave treatment), and staining with the proliferation markers anti-proliferating cell nuclear antigen and MIB 1 was found only in congenital epulis. Both tumor types exhibited pericellular and diffuse cytoplasmic staining for fibronectin and laminin. CONCLUSIONS The hypothesis that congenital epulis and granular cell tumor would exhibit similar reactivity for macrophage markers was confirmed: both were reactive with anti-CD68 and Ki-M1P and nonreactive with MAC387, anti-lysozyme, and 3A5. Intracytoplasmic staining for fibronectin and laminin, which has not been described previously in these tumors, appears to be a characteristic feature common to both tumors. This finding suggests that there could be a disturbance of synthesis and secretion of extracellular matrix proteins or a derangement of their receptor systems. This theory could be supported by the finding of intracytoplasmic CD49e-positive material in two cases.

Diffuse sinusoidal hemangiomatosis of the spleen: A case report with enzyme-histochemical, immunohistochemical, and electron-microscopic findings

Diffuse hemangiomatosis of the spleen is a very rare benign tumor in which the whole spleen is permeated by neoplastic blood vessels. It is occasionally accompanied by severe disturbances of blood coagulation. The histogenesis of this tumor remains obscure. No systematic investigations of the immunophenotype of the neoplastic endothelium have been published. We describe a case of isolated benign diffuse hemangiomatosis of the spleen in which the enzyme-histochemical and immunohistochemical findings suggested an origin in the splenic sinus endothelial cells. Some of the tumor endothelial cells reacted with UEA-1, BMA 120, antibodies against the von Willebrand factor, CD34, and CD8, an antigen which, in man, is expressed only by suppressor/cytotoxic T cells and the endothelial cells of the splenic sinuses. Enzyme-histochemical investigations revealed reactivity for nonspecific esterase and lack of reactivity for alkaline phosphatase--a pattern typical of the sinus endothelial cells. The tumor could be distinguished from other tumors/tumor-like lesions of the spleen that exhibit endothelium with characteristics typical of the splenic sinuses (peliosis, splenoma, littoral cell angioma) on the basis of its histological features. The lack of expression of histiocytic antigens by the tumor endothelium is also evidence against a diagnosis of littoral cell angioma, which also derives from the sinus endothelium. Thus, this tumor could not be identified as any of the recognized tumors/tumor-like lesions of the spleen and it is therefore proposed that it should be designated diffuse sinusoidal hemangiomatosis.

Immunoreactivity of sinusoids in hepatoblastoma: an immunohistochemical study using lectin UEA-1 and antibodies against endothelium-associated antigens, including CD34

Sinusoids are found not only in the normal liver but also in certain liver tumours, including hepatoblastoma, the most common malignant liver tumour in childhood. In this study, sinusoids in 12 hepatoblastomas, of various subtypes, and in normal liver were investigated with UEA‐1 and antibodies against von Willebrands factor, CD31 and CD34 to detect differences of possible diagnostic significance. In the normal liver, staining of sinusoids was seen with all these markers, but it was focal and confined to a few sinusoids near the portal tracts. In hepatoblastoma, the endothelial markers reacted with the sinusoids to varying extents. UEA‐1 and anti‐CD34 usually stained the majority of these vessels, anti‐CD34 staining greater numbers of sinusoids and with greater intensity. Immunostaining revealed that both number and spatial organization of sinusoids in hepatoblastoma are dependent on the subtype. In addition to staining of endothelium, one of the two small cell hepatoblastomas exhibited strong immunoreactivity of the tumour cells for CD34. These findings show that the marked difference in sinusoidal immunoreactivity for CD34 between normal liver and hepatoblastoma could be useful for discriminating between non‐neoplastic liver tissue and highly differentiated fetal hepatoblastoma. Our findings also show that small cell hepatoblastoma, in addition to acute leukaemia, should be considered when immunoreactivity for CD34 is found in small round and blue cell tumours in childhood.

A Comparison of Methods for Heat-Mediated Antigen Retrieval for Immunoelectron Microscopy: Demonstration of Cytokeratin No. 18 in Normal and Neoplastic Hepatocytes

Postembedding antigen retrieval is a well established technique for immunoelectron microscopy; however, many antigens cannot be detected without additional unmasking procedures. This study was undertaken to determine whether microwave oven heating, autoclaving, and pressurized boiling, which are well recognized methods of antigen retrieval for light microscopy, and simple boiling can also be used in electron microscopy. We investigated neoplastic and normal hepatocytes using a commercially available mouse monoclonal antibody against cytokeratin NO. 18 (CK 18). The tissue was fixed in paraformaldehyde/glutaraldehyde and embedded in Lowicryl K4M at -40 C. Ultrathin sections in various buffers were exposed to heat using one of four methods or to pronase at 37 C before incubation with the primary antibody. The secondary antibody was gold-labeled goat anti-mouse antibody. Sections that were not heat-treated remained unlabeled, but heat-treated sections showed immunoreactivity located mainly at the cytoplasmic periphery. Some of the gold particles lay in direct or loose association with intermediate filaments, some were seen in the area of desmosomes, and some did not appear related to any structures. No difference in immunostaining was found among the four methods of heat treatment. The citrate buffer, pH 6.0, and 10 mM EDTA, pH 8.0, generated the best labeling results.

P53 Protein Expression in Hepatoblastoma: An Immunohistochemical Investigation

Mutations of the p53 tumor suppressor gene with immunohistochemically detectable expression of p53 protein have been described in many different malignant tumors. In this study, 12 hepatoblastomas of various subtypes were investigated immunohistochemically with a monoclonal antibody for the expression of p53 protein. Immunoreactivity for p53 protein was found in both small cell tumors investigated and in embryonal areas in two out of eight tumors, but not fetal (eight tumors) or mesenchymal (four tumors) areas. The findings show that immunohistochemically detectable expression of p53 protein, which generally indicates mutation of the gene, may also be present in hepatoblastoma. The finding of p53 protein immunoreactivity in both of the small cell tumors but none of the fetal areas is consistent with a proposal in the literature concerning the histogenesis and differentiation of the various subtypes---that fetal hepatoblastoma is the most well-differentiated and small cell hepatoblastoma the least well-differentiated subtype.

Immunoreactivity of neoplastic and non-neoplastic hepatocytes for CD68 and with 3A5, Ki-M1P, and MAC387 light- and electron-microscopic findings

Abstract The immunohistochemical finding that the macrophage markers KP1, PG-M1 (both CD68) and Ki-M1P occasionally stain epithelial cells prompted a systematic immunohistochemical investigation of liver tissue with these and other macrophage markers. The material investigated comprised normal and cirrhotic liver, four hepatocellular carcinomas, including one fibrolamellar carcinoma, and liver specimens from two cases of extrahepatic biliary atresia and one case of paucity of intrahepatic bile ducts. The macrophage markers KP1, PGM1, Ki-M1P, 3A5, MAC387 and anti-lysozyme were employed. Two cases (one each of extrahepatic biliary atresia and cirrhosis) were investigated by immunoelectron microscopy to determine the subcellular site of reactivity. In the normal liver, only the Kupffer cells reacted with the macrophage markers. However, in neoplastic and non-neoplastic hepatic disorders, all the antibodies (with the exception of anti-lysozyme) stained hepatocytes in at least one case. KP1 produced particularly strong staining. Electron microscopy revealed the reaction product here to be related to lysosome-like granules in the hepatocytes. Therefore, when immunohistochemical investigation of liver biopsy specimens reveals reactivity with macrophage markers, it should be borne in mind that hepatocytes may also be reactive.

Flow cytometric evaluation of nuclear DNA content in hepatoblastoma: Further evidence for the inhomogeneity of the different subtypes

The DNA ploidy pattern of nine hepatoblastomas and three normal liver specimens was investigated by flow cytometry. Areas of unlike differentiation in the same tumor were investigated separately. Normal liver tissue and the fetal subtype were always diploid. Aneuploidy was found in the embryonal subtype. The one case of small cell tumor was also diploid. When the fetal and embryonal areas of the same tumor were analyzed together, there was always an aneuploid peak in the histogram. There are obvious differences in DNA ploidy among the various hepatoblastoma subtypes. Differences in methods used, including the failure in some studies to evaluate areas of unlike differentiation in the same tumor separately, probably account to some extent for the conflicting results of previously reported studies. When flow cytometric analysis of the DNA content of a hepatoblastoma is performed, it is important to ensure that the various types of differentiation in the tumor are represented adequately in the material investigated, especially when conclusions about the prognosis are to be based on these findings.